Ctrl+click a destination for an artillery train that has no schedule configured. Train lands at the destination, guns begin tracking targets, but when the 5-second destination timer expires, guns freeze their activity and targets selected by the artillery remote continue to flash on the map as if fired upon but no action takes place. It took me a while to figure out what was going on, but an artillery train not at a station, with no schedule, and in auto, will not fire at targets. Switching the train back to manual allows it to begin firing again.

This may seem odd, but I believe the way to fix this is to correct the auto-manual behavior. If the train started in manual mode when ctrl+clicked, then once it reaches its destination and the 5 seconds expires / stop is deleted, shouldn't the train return to manual mode? If the user is riding the train and ctrl+clicking a destination, and that train had no schedule other than the temporary one, it is expected that the user would likely wish to manually drive the train once they arrive, and returning the train to manual would help with this while also no longer breaking the artillery.

I have a save with the artillery train in the 'broken' state, not firing while there are flashing x's on the minimap, but it's on the Nauvis Post Apocalypse map, so I'd rather avoid trying to share a 500MB save if at all possible

1. We just leave it as is. "That's just how it works"
2. We change temporary train stops in some way that you describe (what other things might this break?)
3. We change artillery in some way so it doesn't try to shoot related to some condition with temporary stops (what other things might this break?)

I'm leaning more towards #1 but not strongly enough to move this to not-a-bug. I'll leave that up to one of the other developers to decide.

1. We just leave it as is. "That's just how it works"
2. We change temporary train stops in some way that you describe (what other things might this break?)
3. We change artillery in some way so it doesn't try to shoot related to some condition with temporary stops (what other things might this break?)

I'm leaning more towards #1 but not strongly enough to move this to not-a-bug. I'll leave that up to one of the other developers to decide.

I understand the leaning towards #1, and I would do this myself if not for me sitting there for a few minutes straight trying to figure out why the artillery wasn't shooting. I think #2 would work so long as the train only returns to manual if it is left with no stops once the temporary stop was removed. This would mitigate the need for #3 as well.

I noticed the described behaviour as well (though I didn't analyse it in that depth)

Yet I used that behaviour in my current game in my favour: it allows me to take my personal train with outpost building stuff AND an artillery wagon to a remote place and build the outpost without the train shooting at all surrounding biters before I have built any decent defence. As soon as I want the artillery to fire, I set the train control to 'manual' and it happily does its job.

The 5s countdown during which the train is at its temporary job and artillery starts to turn or shoot - that's what confused me

Personally I'd like to see the artillery do nothing in automatic mode outside permanent stations. I'm fine with not changing existing behaviour, too - it's most often close enough to that.

1. We just leave it as is. "That's just how it works"
2. We change temporary train stops in some way that you describe (what other things might this break?)
3. We change artillery in some way so it doesn't try to shoot related to some condition with temporary stops (what other things might this break?)

I'm leaning more towards #1 but not strongly enough to move this to not-a-bug. I'll leave that up to one of the other developers to decide.

I understand the leaning towards #1, and I would do this myself if not for me sitting there for a few minutes straight trying to figure out why the artillery wasn't shooting. I think #2 would work so long as the train only returns to manual if it is left with no stops once the temporary stop was removed. This would mitigate the need for #3 as well.

I'd wish it was #2 (like many others do) and not #1 but I think this better done as a per-train setting for what train does after temporary stop gets destroyed, followed by per-user defaults on temporary stops (conditions, manual/auto). As what I suggest is a rather lengthy way to fix an issue of this margin and, moreover, there's a mod that seems to contain what I just described, I'm afraid this won't be done at all. Or at least until stable is released.

I noticed the described behaviour as well (though I didn't analyse it in that depth)

Yet I used that behaviour in my current game in my favour: it allows me to take my personal train with outpost building stuff AND an artillery wagon to a remote place and build the outpost without the train shooting at all surrounding biters before I have built any decent defence. As soon as I want the artillery to fire, I set the train control to 'manual' and it happily does its job.

The 5s countdown during which the train is at its temporary job and artillery starts to turn or shoot - that's what confused me

Personally I'd like to see the artillery do nothing in automatic mode outside permanent stations. I'm fine with not changing existing behaviour, too - it's most often close enough to that.

Yeah, actually, had the train simply not shot at all once I arrived at the temporary stop, then I would have figured out that I needed to switch to manual to get it to shoot. Maybe the answer is to keep everything else as-is but prevent artillery from shooting while at a temporary stop? This owuld make it more consistent at least, and easier for folks to figure out that they need to switch to manual, etc.
Either that or some more obvious way to prevent artillery from auto-firing.

I'd wish it was #2 (like many others do) and not #1 but I think this better done as a per-train setting for what train does after temporary stop gets destroyed, followed by per-user defaults on temporary stops (conditions, manual/auto). As what I suggest is a rather lengthy way to fix an issue of this margin and, moreover, there's a mod that seems to contain what I just described, I'm afraid this won't be done at all. Or at least until stable is released.

Yeah, there does seem to be unrelated support for #2, and it would fix this problem as well. Folks that want to prevent the train from auto-firing can just switch its mode back to auto after stopping (but they would have to remove all stops from the schedule for that to work).